SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'ad90d5c3ec51220a749f6775c45dfd02cf94b40d5df4a258c78437333557f897' 
  AND token = 'R5/TddDzb9OPyrYgC0GduypKMZN5BsgI8kJ3dUd1+gE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00041

JSON explain

{
  "query_block": {
    "select_id": 1,
    "message": "no matching row in const table"
  }
}